feat(string): support IFEQ/IFNE/IFDEQ/IFDNE in SET command (#3311)

[kirito632]

What this PR does / why we need it

This PR implements the IFEQ, IFNE, IFDEQ, and IFDNE options for the
SET command, resolving #3311.

• IFEQ <value>: only set if key exists and current value equals <value>
• IFNE <value>: only set if key does not exist, or current value differs from <value>
• IFDEQ <digest>: only set if key exists and digest of current value equals <digest>
• IFDNE <digest>: only set if key does not exist, or digest of current value differs from <digest>

Which issue(s) this PR fixes

Closes #3311

Test coverage

• Added 6 C++ unit tests covering all four options, plus GET and TTL combinations
• Added Go integration tests in TestSetConditional covering syntax errors,
  basic behavior, GET/EX combinations, and 10 property-based tests

AI assistance

AI tools were used for the initial implementation draft and test scaffolding.
Logic was reviewed manually against the Redis 8.x documentation and kvrocks
coding conventions.

[PragmaTwice]

Please read https://kvrocks.apache.org/community/contributing#guidelines-for-ai-assisted-contributions.

[kirito632]

Thanks for the pointer. I used AI tools to assist with the initial implementation draft and test scaffolding. I reviewed the logic myself against the Redis 8.x documentation, caught and fixed a wrong test assertion (GET+IFEQ condition-not-met should return the old value, not nil), and cleaned up non-ASCII comments to match kvrocks conventions. I understand the implementation and can explain any part of it.

[kirito632]

Hi @PragmaTwice @jihuayu , I have addressed the review comments and fixed the clang-tidy / Go test issues in my latest commit . I also updated the branch to resolve the out-of-date issue.
PTAL, thanks! (Could you please help trigger the CI for me?)

[jihuayu]

Hi @kirito632. You need to ensure the CI passes before we start the review.

[kirito632]

@jihuayu All CI checks pass locally now:

Lint & Format:

• ✅ ./x.py check format - passed
• ✅ ./x.py check tidy - passed

C++ Unit Tests:

• ✅ ./x.py test cpp - 516 passed, 1 skipped (bitmap test requires USE_BITMAP flag)

Go Integration Tests:

• ✅ go test ./tests/gocase/unit/type/strings/... - all passed (including TestSetConditional).
• ✅ go test ./tests/gocase/integration/replication/... - all 20 test functions passed.

The WRONGTYPE handling fix is in the last commit. Ready for review.

[jihuayu]

@kirito632 Could you please tell me your clang-format and clang-tidy versions?

[jihuayu]

Thanks for you work! Looks good overall, just a few things to fix up:

1. This PR is too large. We prefer one command per PR—please split this into 2–4 smaller PRs.
2. Only add C++ tests if the Go tests can't cover the logic. Please double-check if these are necessary.
3. Please add the following test cases for failure scenarios:

	t.Run("DelEX IFDEQ and IFDNE reject invalid digest length", func(t *testing.T) {
		key := "test-string-key-invalid-digest"
		value := "Hello world"

		require.NoError(t, rdb.Del(ctx, key).Err())
		require.NoError(t, rdb.Set(ctx, key, value, 0).Err())
		require.ErrorContains(t, rdb.Do(ctx, "DelEX", key, "ifdeq", "123456789012345").Err(),
			"exactly 16 hexadecimal characters")
		require.Equal(t, value, rdb.Get(ctx, key).Val())

		require.ErrorContains(t, rdb.Do(ctx, "DelEX", key, "ifdne", "123456789012345").Err(),
			"exactly 16 hexadecimal characters")
		require.Equal(t, value, rdb.Get(ctx, key).Val())
	})

	t.Run("Extended SET GET and NX option on wrong type", func(t *testing.T) {
		require.NoError(t, rdb.Del(ctx, "listkey").Err())
		require.NoError(t, rdb.LPush(ctx, "listkey", "v1").Err())

		require.ErrorContains(t, rdb.Do(ctx, "SET", "listkey", "v", "NX", "GET").Err(), "WRONGTYPE")
	})

[sonarqubecloud]

Quality Gate passed

Issues
16 New issues
0 Accepted issues

Measures
0 Security Hotspots
69.8% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud